High‐throughput phenotyping reveals differential transpiration behaviour within the banana wild relatives highlighting diversity in drought tolerance

Abstract

Crop wild relatives, the closely related species of crops, may harbour potentially important sources of new allelic diversity for (a)biotic tolerance or resistance. However, to date, wild diversity is only poorly characterized and evaluated. Banana has a large wild diversity but only a narrow proportion is currently used in breeding programmes. The main objective of this study was to evaluate genotype‐dependent transpiration responses in relation to the environment. By applying continuous high‐throughput phenotyping, we were able to construct genotype‐specific transpiration response models in relation to light, VPD and soil water potential. We characterized and evaluated six (sub)species and discerned four phenotypic clusters. Significant differences were observed in leaf area, cumulative transpiration and transpiration efficiency. We confirmed a general stomatal‐driven ‘isohydric’ drought avoidance behaviour, but discovered genotypic differences in the onset and intensity of stomatal closure. We pinpointed crucial genotype‐specific soil water potentials when drought avoidance mechanisms were initiated and when stress kicked in. Differences between (sub)species were dependent on environmental conditions, illustrating the need for high‐throughput dynamic phenotyping, modelling and validation. We conclude that the banana wild relatives contain useful drought tolerance traits, emphasising the importance of their conservation and potential for use in breeding programmes.

Diverse responses among wild banana species to vapour pressure deficit, a solution for drought tolerance breeding?

“…9). These values are in line with the general transpiration rate reduction of banana at VPD 2 to 2.3 kPa reported by Carr (2009) and the modelled VPD responses of (Eyland et al ., 2022). The breakpoints in transpiration rate were at similar VPDs compared to other crops (Gholipoor et al ., 2010; Yang et al ., 2012; Ryan et al ., 2016).…”

“…This is in line with our previous observations under fluctuating conditions: M. balbisiana showed together with M. acuminata ssp. errans the most pronounced response by strongly decreasing their transpiration rate (Eyland et al, 2022). As reported by Oren et al (1999), the stomatal reduction was significantly correlated to the maximum gs (Fig.…”

“…M. balbisiana is a parent to many edible bananas belonging to the AAB, ABB and AB genome groups and their subgroups. In line with the conservative behaviour of M. balbisiana in response to VPD (Fig 3-4, Fig 6, Fig 8), it has been indicated in many studies that edible bananas with a high portion of B genes are related to drought tolerance (Ekanayake, Ortiz and Vuylsteke, 1994; Thomas, Turner and Eamus, 1998; Turner and Thomas, 1998; Thomas and Turner, 2001; Vanhove et al ., 2012; Kissel et al ., 2015; Van Wesemael et al ., 2018; van Wesemael et al ., 2019; Eyland et al ., 2021, 2022; Uwimana et al ., 2021). Also M. acuminata spp.…”

“…However, in other crops several genotypes were identified without a breakpoint as they maintained a linear increase in transpiration rate with increasing VPD (Fletcher, Sinclair and Allen, 2007;Gholipoor et al, 2010;Jyostna Devi, Sinclair and Vadez, 2010;Kholová et al, 2010;Yang et al, 2012;Ryan et al, 2016;Sivasakthi et al, 2017). Moreover, temperature and other environmental factors like radiation and soil water potential have been shown to interact with VPD in banana (Eyland et al, 2022). These complex interactions explain why a fixed VPD level per genotype, where a reduction in transpiration takes place, cannot be defined without taking the other environmental conditions in account.…”

“…Most, if not all, cultivars have genomes consisting of different proportions of A- and B-genome chromosomes and/or recombinant chromosomes originating from different parents. Similar to other tropical species, bananas are very sensitive to VPD, with reductions in transpiration when VPD exceeds 2 – 2.3 kPa (Aubert and Catsky, 1970; Carr, 2009; Eyland et al ., 2022). Thomas et al (1998) observed a diverse response in three banana cultivars with different genomic constitutions.…”