Local adaptation optimizes photoprotection strategies in a Neotropical legume tree under drought stress

Photoprotection is a plant functional mechanism to prevent photooxidative damage by excess light. This is most important when carbon assimilation is limited by drought, and as such, it entails a trade-off between carbon assimilation vs stress avoidance. The ecological adaptation of plants to local water availability can lead to different photoprotective strategies. To test this, we used different provenances of Caesalpinia spinosa (Mol.) Kuntze (commonly known as ‘tara’) along a precipitation gradient. Tara is a Neotropical legume tree with high ecological and commercial value, found in dry tropical forests, which are increasingly threatened by climate change. Morphological and physiological responses of tara provenances were analysed under three different treatments of drought and leaflet immobilization, i.e., light stress, in a common garden greenhouse experiment. Tara quickly responded to drought by reducing stomatal conductance, evapotranspiration, photochemical efficiency, carbon assimilation and growth, while increasing structural and chemical photoprotection (leaflet angle and pigments for thermal dissipation). Leaflet closure was an efficient photoprotection strategy with overall physiological benefits for seedlings as it diminished the evaporative demand and avoided photodamage, but also entailed costs by reducing net carbon assimilation opportunities. These responses depended on seed origin, with seedlings from the most xeric locations showing the highest dehydration tolerance, suggesting local adaptation and highlighting the value of different strategies under distinct environments. This plasticity in its response to environmental stress allows tara to thrive in locations with contrasting water availability. Our findings increase the understanding of the factors controlling the functional ecology of tara in response to drought, which can be leveraged to improve forecasts of changes in its distribution range, and for planning restoration projects with this keystone tree species.

First record of the seed beetle Merobruchus paquetae (Chrysomelidae, Bruchinae) in the exotic tree Leucaena leucocephala

We record for the first time the host association of the seed beetle Merobruchus paquetae with the invasive legume tree Leucaena leucocephala. This species of beetle was associated in Colombia to the native legume tree Pseudosamanea guachapele.

Lectotypification of Albizia lathamii (Leguminosae: Mimosoideae)

The name Albizia lathamii (Leguminosae: Mimosoideae), an endemic legume tree of Peninsular India and considered Critically Endangered, is herewith lectotypified with the specimen collected by H.A. Latham and named by R.S. Hole (1912). The online herbarium image of the lectotype at K and the original illustration in the protologue by Hole are also provided. Besides, the diversity of endemics of the genus in India is clarified.