Regulation of stamen maturation in barley and Arabidopsis


We study two major aspects of plant development: how it is shaped by spatiotemporal patterns of hormone signaling, and what are the ultimate cellular functions activated by hormones that lead to cell fates as disparate as proliferation, elongation or degeneration.

Specifically, we focus in the synchronized maturation of stamens and pistils that favors self-pollination in barley and Arabidopsis. In several plant species, timely stamen maturation is critically dependent on signaling by the jasmonate (JA) family of lipidic prohormones and hormones [1-3]. In Arabidopsis, JA promotes (i) stamen filament growth by cell elongation so that anthers reach the pistil for pollination [4-6]; and (ii) anther opening via the degeneration of a single specialized cell type, the stomium, to allow pollen release [1]. JA signaling induces the expression of MYB transcription factors that are the master regulators of the transcriptional program leading to successful stamen maturation [4-6]. Additionally, JA signaling activates a network of JA biosynthesis enzymes and transcriptional repressors (JAZs) that are believed to create positive and negative feedback regulatory loops [4,6].


Our research aims at:

(a) understanding the spatiotemporal dynamics of the JA signaling network and its function in patterning stamen cell fate decisions;

(b) identifying the ultimate proteins and mechanisms activated by JA signaling to achieve filament cell expansion and stomium degeneration.

(c) uncovering other signaling pathways necessary for stamen maturation

We are developing and using existing barley genetic resources, such as mutant collections, natural variation in wild and cultivated barley, and their corresponding mapping populations to identify genes participating in stamen maturation. We also take advantage of Arabidopsis to follow the dynamics of JA signaling components in maturing stamens.

Barley florets before anthesis and during synchronized maturation of reproductive organs. Anther dehiscence coincides with the beginning of stamen filament elongation. By the time stamens reach maximum length pistil self-pollination has occurred.

A deep understanding of stamen maturation will provide ideal targets to effectively control male fertility in crops. This is an essential and unfulfilled need for efficient breeding and hybrid seed production, one of the promising solutions to the challenges of food security since hybrid crops tend to grow better and with higher yields than their parents via heterosis.



[1] Sanders et al (2000) Plant Cell 12, 1041; [2] Stintzi & Browse (2000) Proc Natl Acad Sci U S A 97, 10625; [3] Riemann et al (2003) Plant Physiol 133, 1820; [4] Mandaokar et al (2006) Plant J 46, 984; [5] Cheng et al (2009) PLoS Genet 5, e1000440; [6] Reeves et al (2012) PLoS Genet 8, e1002506

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