Low temperature‐induced aberrations in male and female reproductive organ development cause flower abortion in chickpea

Abstract

Chickpea (Cicer arietinum L.) is susceptible to low temperature (LT) at reproductive stage. LT causes flower abortion and delays pod set in chickpea until terminal drought becomes an issue, thereby decreasing yield potential. In chickpea, flower and anther/pollen development as well as LT‐induced abnormalities on anther and pollen development are described inadequately. In the present manuscript, we report flower development stages, anther development stages, and aberrations in male gamete formation in chickpea under LT. Flower length was linearly correlated to flower and anther stages and can be used to predict these stages in chickpea. LT affected male gamete development in a flower/anther age‐dependent manner where outcome ranged from no pollen formation to pollen sterility or no anther dehiscence to delayed dehiscence. In anthers, LT inhibited microsporogenesis, microgametogenesis, tapetum degeneration, breakage of septum and stomium, and induced pollen sterility. Whereas disruption of male function was the prime cause of abortion in flowers below vacuolated pollen stage, flower abortion was due to a combination of male and female reproductive functions in flowers with mature pollen. The study will help in elucidating mechanisms governing flower development, anther and pollen development, and tolerance/susceptibility to LT.

Developing Climate-Resilient Chickpea Involving Physiological and Molecular Approaches With a Focus on Temperature and Drought Stresses

“…The causes of flower abortion in sensitive genotypes of chickpea are fairly well understood. It is well documented that male gametophyte of chickpea is highly sensitive to cold stress and in genotypes sensitive to cold, both microsporogenesis and subsequent pollen development are inhibited at temperatures below 10°C (Sharma and Nayyar, 2014;Kiran et al, 2019). Identification of flower and anther development stages in chickpea allowed studying the impact of cold at different flower development stages (Kiran et al, 2019).…”

“…It is well documented that male gametophyte of chickpea is highly sensitive to cold stress and in genotypes sensitive to cold, both microsporogenesis and subsequent pollen development are inhibited at temperatures below 10°C (Sharma and Nayyar, 2014;Kiran et al, 2019). Identification of flower and anther development stages in chickpea allowed studying the impact of cold at different flower development stages (Kiran et al, 2019). Flowers of different development stages react differently to cold stress (Kiran et al, 2019) e.g., low temperatures terminate microsporogenesis in flowers at premeiotic stage of anthers and microgametogenesis in those at tetrad stage.…”

“…Identification of flower and anther development stages in chickpea allowed studying the impact of cold at different flower development stages (Kiran et al, 2019). Flowers of different development stages react differently to cold stress (Kiran et al, 2019) e.g., low temperatures terminate microsporogenesis in flowers at premeiotic stage of anthers and microgametogenesis in those at tetrad stage. In anthers at young microspore stage, low temperatures inhibited anther dehiscence but did not inhibit development of microspores to mature pollen stage.…”

“…Exposure at mature pollen stage delayed anther dehiscence and induced partial pollen sterility (Kiran et al, 2019). The quantum of low temperatures induced pollen sterility also depends upon the age of the flower with older flowers producing less amount of sterile pollen as compared to younger flowers, e.g., low temperature treatment at young microspore stage led to complete sterility of pollen whereas those at vacuolated microspore stage 23.59% pollen were viable, at vacuolated pollen stage 52.4% pollen were viable, at mature pollen stage 65.5% pollen were viable (Kiran et al, 2019). Apparently, male gametophytes of younger flowers are more prone to damage by cold stress as compared to the older ones.…”

“…Chilling stress also has an adverse effect on gynoecium to impair ovule function; Srinivasan et al (1998) reported missing embryo sacs in some chickpea cultivars, which reduced the number of fertilized ovules in all cultivars during cold stress. Chilling stress reduces ovule viability, stigma receptivity, and pollen load on stigma (Kiran et al, 2019). While studying flower abortion due to cold stress in chickpea, it was observed that the older flowers, that have sufficient viable pollen were also aborted (Kiran et al, 2019).…”