Carotenoids were extracted and measured using high- performance liquid chromatography(HPLC) according to xu et al. (2006) with some modifications. Juice sacs(0.2 g fresh weight, FW) were ground to a fine powder in liquid nitrogen, and the carotenoids were then released from the powder by mixing with methanol(350 uL), chloroform(700 uL) and ddH20(350 uL) and vortexed for 20 sto homogenize the suspension. The subnatant was transferred to a new centrifuge tube, and the extraction procedures were repeated 1-2 times, after which the combined chloroform lay- ers were evaporated to dryness under vacuum conditions at room temperature