Why does C4 photosynthesis rarely evolve in trees?

C4光合作用是一种超高效的植物生理模式，被我们最具生产力的粮食和生物能源作物所使用，包括玉米，甘蔗和芒草。它在近70个植物谱系中独立进化。尽管有这些多重进化，C4光合作用在树木中是极其罕见的，仅在大戟科的少数树种中有记载，这是一个重要的石油和橡胶生产家族。这个博士研究生将调查为什么C4光合作用很少在树木中进化。为了做到这一点，学生将在温室和田间实验中观察不同光合作用背景的大戟科树木的水和氮利用经济。野外工作将在广州华南植物园的中国科学院校园内进行，那里有大量的大戟科树木。通过对具有不同光合背景的大戟科树木的地理分析，学生将说明这些物种的生态和地理分布如何促进该家族复杂光合状态的演变。

C4 photosynthesis is an ultra-efficient mode plant physiology that is used by our most productive food and bioenergy crops, including maize, sugarcane, and miscanthus. It has evolved independently in nearly 70 plant lineages. Despite these multiple evolutions, C4 photosynthesis is extremely rare in trees, having only been documented in a handful of tree species in the Euphorbiaceae, a family important for oil and rubber production. This PhD studentship will investigate why C4 photosynthesis rarely evolves in trees. To do this, the student will look at the water- and nitrogen- use economies of Euphorbiaceae trees of differing photosynthetic backgrounds in both greenhouse and field experiments. Field work will take place at the Chinese Academy of Sciences campus at the South China Botanical Garden in Guangzhou, which houses a collection of Euphorbiaceae trees. Through biogeographic analyses of Euphorbiaceae trees with different photosynthetic backgrounds, the student will illustrate how the ecological and geographic distributions of these species may have facilitated the evolution of complex photosynthetic states in this family.