Introduction:

Abiotic stress caused by cold or water-deficit alters many cellular processes that modificate the physiology and biochemistry of plants, which reduces yield of agricultural crops. Gibberellins are phytohormones that can induce growth and development of the plants. There are many genes whose transcription is modified during abiotic stress or by exogenous-gibberellins application; some of them encode for proteins such as LEA that confer protection against low temperature and dehydration, WRKY and FT that take part in the response to abiotic stress, FT that regulates the flowering time, and GA20ox1 that synthesized gibberellins. The understanding of molecular mechanism that regulates the plant responses to abiotic stress or exogenous gibberellins application is essential for Capsicum annuum (pepper) agriculture improvement. To this aim, we have proceeded to study the effect of biotic stress and exogenous phytohormones on C. annuum development, mainly in fruit (chili) production and expression of genes involved in the response to these conditions.

Method:

The genome of Capsicum annuum contains homologues to the proteins LEA, WRKY, FT and GA20oxy, so we estimate by Real-Time PCR (qPCR) and phenotype analysis, the gene expression and fruits production in plants grown under abiotic stress and after treatment with exogenous gibberellins.

Results:

The transcripts of CaLea73 and CaWRKY40 increased by cold stress in leaves. While, CaGA20ox1 expression was down-regulated by cold stress, GA3, and hydric stress-GA3 in leaves. This effect was also observed in flower buds of plants grown under water-deficit, treated with gibberellins or hydric stress-GA3; curiously, the transcripts from this gene became slightly abundant in plants grown under water-deficit. CaFT transcription was induced by cold stress and GA3 in leaves and flower buds, respectively; however, transcription of this gene was almost abolished by hydric stress and GA3-hydric stress in both tissues. Cold stress and exogenous phytohormones raised the fruits production.

Conclusion:

According with these results, we propose that cold treatment induces the plant defense mechanisms through activation of transcription factors like WRKYs and LEA proteins and increases the plant development through induction of signaling pathway of FT. Our study contributes to understanding on molecular mechanisms governing the responses to abiotic stress and the participation of the gibberellins in C. annuum development and to improve the yield of the chili crop.

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