Reproductive water supply is prioritized during drought in tomato

Abstract

Reproductive success largely defines the fitness of plant species. Understanding how heat and drought affect plant reproduction is thus key to predicting future plant fitness under rising global temperatures. Recent work suggests reproductive tissues are highly vulnerable to water stress in perennial plants where reproductive sacrifice could preserve plant survival. However, most crop species are annuals where such a strategy would theoretically reduce fitness. We examined the reproductive strategy of tomato (Solanum lycopersicum var. Rheinlands Ruhm) to determine whether water supply to fruits is prioritized above vegetative tissues during drought. Using optical methods, we mapped xylem cavitation and tissue shrinkage in vegetative and reproductive organs during dehydration to determine the priority of water flow under acute water stress. Stems and peduncles of tomato showed significantly greater xylem cavitation resistance than leaves. This maintenance of intact water supply enabled tomato fruit to continue to expand during acute water stress, utilizing xylem water made available by tissue collapse and early cavitation of leaves. Here, tomato plants prioritize water supply to reproductive tissues, maintaining fruit development under drought conditions. These results emphasize the critical role of water transport in shaping life history and suggest a broad relevance of hydraulic prioritization in plant ecology.

The transcriptome of soybean reproductive tissues subjected to water deficit, heat stress, and a combination of water deficit and heat stress

“…An additional interesting finding that emerged from the data shown in Figure 2 is that the transcriptomic response of all reproductive tissues studied included fewer transcripts (359, 1155, 204, 525, and 822 transcripts in pod, sepal, anther, stigma, and ovary, respectively) than that of leaf (over 4600 transcripts) in response to WD stress. This finding suggests that in contrast to leaf, reproductive tissues might be better protected during WD stress, perhaps because they represent a primary sink tissue of the plant (Harrison Day et al., 2022). In contrast to the transcriptomic responses of leaf, pod, and sepal (over 3000, 2400, and 4300 transcripts, respectively), the transcriptomic responses of anther, stigma, and ovary to HS were more robust (over 7000 transcripts in each tissue).…”

“…Interestingly, compared to leaf, the expression of most transcripts encoding ABA biosynthesis and degradation enzymes was not upregulated in reproductive tissues during WD (Figure 6a). This finding could suggest that during WD, ABA is mobilized from leaves or roots to reproductive tissues, rather than synthesized/degraded in these tissues, or that reproductive tissues are less sensitive than other plant tissues to WD due to being a prime sink tissue (Harrison Day et al., 2022).…”

Constant hydraulic supply and ABA dynamics facilitate the trade-offs in water and carbon

“…We additionally conclude that soil drought, by suppressing preferential stomatal behavior, could impede the competitive strength of plant species with differed preferential stomatal conductance, hence changing the competitive structure of entire plant communities (Hautier et al, 2009). On the other hand, mechanisms that maintain constant hydraulic supply across soil-plant system, especially during soil drying, could provide a great advantage in growth and development of a species Bourbia et al, 2022;Harrison Day et al, 2022). Such mechanisms could be a long and dense root system with low hydraulic conductance (Abdalla et al, 2022;Cai et al, 2022), long and dense root hairs (Carminati et al, 2017;Marin et al, 2021), plasma membrane aquaporin (Caldeira et al, 2014), root mucilage (Ahmed et al, 2014;Carminati et al, 2016) and/or root symbiosis with arbuscular mycorrhizal fungi (Bitterlich et al, 2018;.…”

Plant water use theory should incorporate hypotheses about extreme environments, population ecology, and community ecology

“…During drought, plants might be more limited by water than by carbon, so they may prioritize allocation to reproduction over that to leaves, not only because of fitness but also because water loss may be higher from leaves than from flowers or fruits. In stressful conditions, prioritization of water for fruit growth has been reported in Solanum lycopersicum (tomato; Harrison Day et al ., 2022) while prioritization of transpiration in flowers occurs in Glycine max (soybean; Sinha et al ., 2022), and prioritization of storage occurs in Picea abies (spruce). There is also increased allocation to reproduction when water is limited during seasonal and El Niño drought in tropical forests (Detto et al ., 2018).…”