Background

The world wheat production amounts to little more than 600 million tonnes (MT) per year. The main producing countries are China, India and USA (230 MT), and half of the world production is generated in developing countries and only 10% of production is exported, mainly by the United States, Canada, Australia and France. It is estimated that in 2050 there will be over 8 billion people in the world and should increase production by over 30% (^{Rosegrant and Agcaoili, 2010}); unfortunately, it is predicted that over the next 40 years wheat production in developing countries could be reduced by 29% due to global warming (^{The Lancet, 2008}) and the threat of disease (^{Singh et al., 2008}; ^{Rosegrant and Agcaoili, 2010}).

The national wheat production and imports to our country have shown variations in the last 12 years. Production fell from 3.5 to 2.8 MT of 2000-2004; however, since 2005 it has picked and harvested 3.9 MT 2012; among other things, due to the higher productivity of new varieties. From 2000-2012 were imported per year over 3 MT, reaching this volume to 3.7 MT in 2005. It is important to recognize within the scenario as wheat importer country, the United States as the main exporting country, not the provider barn importing countries, as their indicators are not encouraging, so, it would be wrong to think that the United States of America, is the solution for Mexico to fill the demand for wheat; it is more important to implement programs to strengthen research, to encourage the production and marketing in irrigated areas and contemplate rainfed areas as an alternative to increase plantings, where we can allocate to wheat over a million hectares which could contribute about 2.5 million tonnes (^{Villaseñor, 2000}).

In Mexico, wheat represents 21% of consumption of basic grains and is second only to corn, with a per capita consumption of 52 kg per year. Sonora, Guanajuato, Baja California and Michoacan, concentrated 62% of the acreage in 2012 was 762 000 ha. Production in that year was 3.9 MT and had a value that exceeded 15 billion pesos. The Northwest produces about 55% and consumes 12%; the main consumer area is the south-central claiming nearly 60% of the national grinding region. Mobilize 1.5 MT of Mexicali or South of Sonora to the centre is unaffordable, because the freight cost per ton is closer to $600, while the freight of wheat produced in the Bajío or the Highlands to the mills in these regions varies $190 to $300 (^{SIAP, 2012}). The deficit of wheat in Mexico, its cost-rising internationally and the need to increase domestic production were causes for creating in 2004 the System Product Wheat (CONASIST), where the issue of culture was analysed and determined that it was urgent to strengthen the improvement to generate more and better varieties; was as a draft 2006-2008 that allowed free 10 varieties currently planted on more than 50% of the area nationally financed. CONASIST in 2010 also boosted fund the improvement, so the aim of this is to indicate how it is done through the support of SAGARPA-CONACYT Sector Fund Project No. 146 788, which is valid for 2011-2016 and with the goal for delivering 25 varieties.

The genetic improvement of wheat in Mexico

Wheat improvement programs in Mexico, since its inception in the mid-40's to date, have worked two cycles per year in contrasting environments have been entrepreneurs in their techniques employed and have used diverse germplasm to incorporate favourable genes, which lets summarize their contributions as follows: the selection of seedlings in winter and summer with different photoperiods allowed expression of Ppd1 and Ppd2 (^{Rajaram, 1995}) genes, resulting in the development of varieties with wide adaptation in various parts of world. Stem rust is genetically controlled in 1955 thanks to the effect of Sr2 gene (^{Borlaug, 1968}). The source of dwarfing in Norin 10 allowed incorporating the Rht1 and Rht2 genes that caused reduction in plant height that allowed during the sixties release about 15 semidwarfs that exceeded the barrier of 4.5 t ha^-1 in the Northwest and came in sometimes up to 8 t ha^-1 (^{Borlaug, 1969}). In the seventies and eighties the introduction of germplasm and recombination between spring wheats habit with winter (I x P) and the recombination between wheat and barley, led to improved adaptation, stability, yield and disease resistance, thanks to the 1BL/1RS translocation, which carry genes favourable as Lr26, Sr31, Yr9 and PM8 (^{Villarreal, 1995}). During the 80's more emphasis was placed on the evaluation of seedlings in different environments and recombination of wheat intensified with compatible species of Triticum tauschii, Thinopyrum spp. and Triticum dicoccoides (^{Villarreal, 1995}), for horizontal resistance to leaf rust, identifying gene complexes under additive and the Lr13 (^{Rajaram et al., 1988}), Lr34 (^{Singh, 1992}) and Lr46 (^{Huerta and Singh, 2000}).

In recent years there has been work on the genetic control of yellow rust and quality improvement. In yellow rust has been found in adult plant resistance thanks to Yr18 (^{Singh and Rajaram, 1995}), Yr28 (^{Singh et al., 2000}) and Yr29 genes (^{William et al., 2003}). In terms of quality, we have studied the patterns of quality of Mexican wheats, with special emphasis on storage proteins (glutenin and gliadin) that confer improved quality, identifying the best combination of high molecular weight of glutenin (Glu APM), low molecular weight (Glu-BPM) and gliadin (Gli) (^{Wang et al., 2010}), which has improved the quantity and quality of proteins of Mexican wheats (^{Peña et al., 2004}). The results of genetic improvement of wheat in Mexico can be synthesized in the release of 234 varieties that have been the platform of national production.

The research project No. 146788, effective 2011-2016

In the research project funded by SAGARPA-CONACYT sector fund, called “system of improvement to produce rust resistant varieties, high yield and high quality for a sustainable wheat production in Mexico” 44 researchers of the National Research Institute National Forestry, Agriculture and Livestock (INIFAP), International Maize and Wheat Improvement Center (CIMMYT), Chapingo Autonomous University (UACH) and Postgraduate College of Agricultural Sciences (COLPOS) and aims that improvement programs and supporting disciplines in plant pathology and industrial quality interact more on the introduction of germplasm, genetic recombination and selection in segregating, to generate uniform lines evaluated in national selection nurseries (VNST) and national performance tests (ENRT).

Germplasm from around the world will be introduced to enrich the genetic background that allows progress in the medium and long term, segregating germplasm was evaluated in different production conditions in localities northwest, northeast, High Valley, El Bajío, the Sierra Tarasca and Mixteca Oaxaca, seeking greater selection pressure conditions. Selected for tolerance to heat stress in dry tropical locations and drought tolerance in poor rainfed sites in northern Mexico. The derived lines were tested in nurseries selection and yield tests on rainfed and irrigation, which will be evaluated during the spring-summer and autumn-winter cycles, respectively; in summer experiments were set up in 30 locations in States ranging from Oaxaca to Chihuahua, while in winter it will be established under normal irrigation and limited up to 30 trials tested from Oaxaca watering until BC 150 N. In VNST genotypes were tested and the town will be taken as repetition, selecting for agronomic characters, plant disease and industrial quality. In ENRT 50 genotypes under the experimental design Alfa lattice, where are selected by performance, reaction to diseases, agronomic traits and quality parameters will be evaluated. It aims to collect data from up to 120 evaluations in four years, which is possible, in coordination with wheat product chain system, realize the successful release of varieties in a short time.

It will be important to resume the monitoring, identification, distribution and frequency of physiologic races of leaf rust and yellow, to understand the dynamics of these diseases and required to achieve their genetic control genes. Year after year, during the autumn -winter cycles and spring- summer, they will be collected nationwide samples of infected leaves in commercial plantings and experimental plots; will also be established with national testing, trap nurseries to facilitate identification of races. The collected samples were processed in the National Laboratory Rusts (LANARET) INIFAP for identification. Regarding the new race of stem rust, Ug99, the selected lines will be evaluated in Kenyan towns through CIMMYT, which will also release varieties with resistance to this rust.

The manufacturing quality is an important component in selecting candidates for release lines. Parents will be characterized by electrophoresis to identify the allelic variants of glutenin high and low molecular weight associated with the strength and extensibility of the dough, and genotypes with allelic combinations are most appropriate for use in new crosses. For bread, wheat selection for characters will be on hard endosperm, high sedimentation volume, low enzymatic activity, protein content, strength and extensibility of the dough, test weight, volume of bread, gluten and crumb quality. For macaroni (crystalline) wheats, the selection will be to test weight, grain hardness, black tip, white belly, glassy grain sedimentation volume, protein content, strength and extensibility, and yellow semolina.

Progress of the research project no. 146788

The project started in February 2011 and culminated in February 2016, organized through five stages, one per year. We indicate the progress of the first four stages.

CIMMYT has introduced and characterized more than 4 000 entries, highlighting the selections for resistance to Fusarium and UG99 as well as high quality wheat technology.

The genetic improvement has been made by the programs INIFAP-rainfed and INIFAP-irrigation CIMMYT- flour and CIMMYT durum, who have advanced their germplasm for eight cycles of recombination and selection (two per year) and have generated close to 9 500 lines tested in preliminary performance tests.

We have evaluated different nurseries and national tests; for irrigation of 1 to 4° VISTRI and 8° to 11° ENTRI, proving the lines in about 150 different conditions; while for rainfed 16° to 19° and 15° VSTHT 18° ERTHT, testing the lines at 108 different sites. 24 lines have been marked for release during the four years.

We have collected about 750 samples rusts, mostly yellow rust, being processed in LANARET that was built with the support of the project and was virtually completed in August 2014. The samples processed to date (30%) allow recognize great variability of physiological races of yellow rust.

Up to this date, the following varieties have been released: Anatoly C20011, Bacali F2011, Luminaria F2013, Baroyeca Oro C2013, Quechehueca Oro C2013, Borlaug 100 F2014 and Alondra F2014. In process for registration: Bacorehuis “s”, Conatrigo “s”, Barobampo “s”, Conasist “s”, Don Carlos “s”, Valles “s” and Acolhua “s”. In the autumn-winter cycle/2014-2015 are in their second year of characterization 10 lines candidates to release the most outstanding (3-4) in late 2015 and in its first year of characterization 14 lines to deliver the best (6 8) during 2016.

Conclusions

With the research project no. 146 788 has been achieved greater interaction among institutions and especially between different improvement programs, which has allowed strengthening to generate best lines. The network of national yield trials has been a good strategy to identify best varieties advanced to free lines, which are exceeding up to 10% than the best controls. The monitoring of physiologic races of rust is an action to be performed continuously in order to have them well identified and achieve their genetic control, for which the construction of LANARET was very supportive.